well J, what us CA people do is, take our spring out of our mag, cut the end stack of coils off till there are only 3 coils left, strech those out a little and then we can load 14 rounds into them and one in the pipe. Works great and that is the only difference. If your 15 round mags has 10 coils at the bottom, cut them and you'll be able to load 18 -20. Order a new one incase you cut too many coils.
I would say most buy the Sigma with the 16 round mags, except the CA. people. I think S&W is the only place to get them at this time.
Oh hey Rich, I am gettin a M&P 45 FS in a week. I wanted to get the two tone one but there is a 6 mo waiting list, so I've been told.
I take it you survived your little Sigma quality test. What exactly did you do to it?
Summitarms.com, has 40, and 9, mags for 25.00, for the Sigma. They may be used, police surplus.